The St. Louis Cardinals entered the 2023 MLB season as the favorite in the wide-open NL Central. Yet by the end of April, the Cardinals were 10-19 — their worst record in the opening month since 1973 and their first losing record in April since 2007. That slide would continue for the rest of the year as the team was unable to sustain any sort of momentum. The team was 14 games under .500 by the All-Star break and would finish the year at 71-91 —a full 21 games back in the division and cementing a last-place finish.

After such a disappointing season, there are so many players to blame and fingers to point — namely on the pitching staff that allowed a mediocre 5.12 runs per game this year. Here are the Cardinals players who cost the team the most in 2023:

Miles Mikolas

After a 3.29 ERA and an All-Star Game appearance in 2022, the Cardinals were counting on more ace-like performances from Miles Mikolas in 2023. The 35-year-old was a workhorse for the Cardinals, leading MLB in innings pitched (226) and batters faced (860), but his ERA ballooned to 4.78. He was especially poor to begin the year, posting a 7.46 ERA in his first five starts, then, after a solid middle of the season, ended the campaign with a 6.15 ERA across his final 10 appearances.

Mikolas was simply not able to miss enough bats, as his 226 hits given up were the most in the league and 2,5 more per nine innings than in 2022. The big difference was his fastball. Worth 14 runs in 2022, Miles Mikolas' heater was worth -13 runs in 2023 — putting him in the sixth percentile among all MLB pitchers.

Jack Flaherty

In the end, it was inconsistency that killed Jack Flaherty. Five scoreless starts of at least five shutout innings were offset by an ERA over 5.00  in both May and June. Flaherty finished with a 4.43 ERA in 20 starts with STL before the club traded him to Baltimore, but his inability to put together multiple solid starts in a row really seemed to encapsulate the issues the Cardinals had with their starting rotation this season.

Ryan Helsley

While he finished with a good stat line for the season (2.45 ERA, 14/19 save opportunities) his three blown saves in April put the Cardinals behind the eight-ball. His first came on Opening Day, when Ryan Helsley gave up two runs at home to the Toronto Blue Jays, turning a 9-8 advantage to a 9-10 deficit. If the right-hander converts those three opportunities, St. Louis is only three games under .500 to end the month and still well within the conversation in the NL Central. Over the course of a long season, small details like these matter.

Giovanny Gallegos

One of the better high-leverage relievers for the Cardinals over the last few years, Gallegos came in with a 2.84 ERA since the start of 2019. He ended the season with a 4.42 ERA, the worst of his career, to go with six blown saves in 16 chances — making him more culpable than Ryan Helsley. Gallegos emerged as the main closer in May and proceeded to earn the loss in two of his first three appearances that month during the team's embarrassing eight-game losing streak. He would blow three more saves in the month of June as St. Louis slid even further back in the NL Central.

By then, Jordan Hicks returned as the closer, thus blocking Gallegos from any further late-inning mishaps at Busch Stadium.